A mass spectrometry-based Protein Microcharacterization Facility has been established within the Mass Spectrometry Workgroup in LSB. The purpose of the Facility is to provide state-of-the-art mass spectrometric characterization of proteins. This includes proteins separated by gel electrophoresis, obtained from expression systems, isolated from immunoprecipitation experiments, and identification of posttranslational modifications and adducts. The Facility also provides MS-based proteomics identifications from 2-D gel electrophoresis in collaboration with other groups. Additionally, the PMCF has begun a monthly User's Forum and training on use of open access MALDI/TOF instrumentation.